WiiBrewβ

PNGU

PNGU is a library for Wii and GameCube that 'wraps' the famous libpng and facilitate png handling and conversions to the native Wii/GC formats. The PNG format has some properties which make it interesting: A background color, a list of transparent colors, alpha channel, it doesn't modify the colors (as jpeg does when compression), open format. The source code of the library is included in the download package.

Limitations

Image width and height should be a multiple of 4 (when converting to 4x4 textures)

Doesn't handle images of 1, 2 or 4 bits per channel.

Doesn't handle paletized images.

Endianness problems when using it on a little endian machine (x86 for example) no problems on the Wii/GC.

Download as a library

If you download the source from above, you will have to include the c and h files to your project, so I have added a makefile and now you can "make" and "make install" the library.
Download: http://www.mediafire.com/?z6yojcmmh4s8pml